diff options
| author | Chao Peng <chao.p.peng@linux.intel.com> | 2023-10-27 21:22:02 +0300 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2023-11-14 16:01:04 +0300 |
| commit | 8dd2eee9d526c30fccfe75da7ec5365c6476e510 (patch) | |
| tree | 667e9cb285e792d63240df26908b4c9df498b1f2 /include/linux/kvm_host.h | |
| parent | 90b4fe17981e155432c4dbc490606d0c2e9c2199 (diff) | |
| download | linux-8dd2eee9d526c30fccfe75da7ec5365c6476e510.tar.xz | |
KVM: x86/mmu: Handle page fault for private memory
Add support for resolving page faults on guest private memory for VMs
that differentiate between "shared" and "private" memory. For such VMs,
KVM_MEM_GUEST_MEMFD memslots can include both fd-based private memory and
hva-based shared memory, and KVM needs to map in the "correct" variant,
i.e. KVM needs to map the gfn shared/private as appropriate based on the
current state of the gfn's KVM_MEMORY_ATTRIBUTE_PRIVATE flag.
For AMD's SEV-SNP and Intel's TDX, the guest effectively gets to request
shared vs. private via a bit in the guest page tables, i.e. what the guest
wants may conflict with the current memory attributes. To support such
"implicit" conversion requests, exit to user with KVM_EXIT_MEMORY_FAULT
to forward the request to userspace. Add a new flag for memory faults,
KVM_MEMORY_EXIT_FLAG_PRIVATE, to communicate whether the guest wants to
map memory as shared vs. private.
Like KVM_MEMORY_ATTRIBUTE_PRIVATE, use bit 3 for flagging private memory
so that KVM can use bits 0-2 for capturing RWX behavior if/when userspace
needs such information, e.g. a likely user of KVM_EXIT_MEMORY_FAULT is to
exit on missing mappings when handling guest page fault VM-Exits. In
that case, userspace will want to know RWX information in order to
correctly/precisely resolve the fault.
Note, private memory *must* be backed by guest_memfd, i.e. shared mappings
always come from the host userspace page tables, and private mappings
always come from a guest_memfd instance.
Co-developed-by: Yu Zhang <yu.c.zhang@linux.intel.com>
Signed-off-by: Yu Zhang <yu.c.zhang@linux.intel.com>
Signed-off-by: Chao Peng <chao.p.peng@linux.intel.com>
Co-developed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Fuad Tabba <tabba@google.com>
Tested-by: Fuad Tabba <tabba@google.com>
Message-Id: <20231027182217.3615211-21-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'include/linux/kvm_host.h')
| -rw-r--r-- | include/linux/kvm_host.h | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index a6de526c0426..67dfd4d79529 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -2357,14 +2357,18 @@ static inline void kvm_account_pgtable_pages(void *virt, int nr) #define KVM_DIRTY_RING_MAX_ENTRIES 65536 static inline void kvm_prepare_memory_fault_exit(struct kvm_vcpu *vcpu, - gpa_t gpa, gpa_t size) + gpa_t gpa, gpa_t size, + bool is_write, bool is_exec, + bool is_private) { vcpu->run->exit_reason = KVM_EXIT_MEMORY_FAULT; vcpu->run->memory_fault.gpa = gpa; vcpu->run->memory_fault.size = size; - /* Flags are not (yet) defined or communicated to userspace. */ + /* RWX flags are not (yet) defined or communicated to userspace. */ vcpu->run->memory_fault.flags = 0; + if (is_private) + vcpu->run->memory_fault.flags |= KVM_MEMORY_EXIT_FLAG_PRIVATE; } #ifdef CONFIG_KVM_GENERIC_MEMORY_ATTRIBUTES |